The present invention relates to a video data processing apparatus and a method thereof for performing an inverse 2:3 pull-down process for a television signal of which a film material has been processed with 2:3 pull-down process so as to remove redundant fields. In addition, the present invention relates to a video data encoding apparatus and a method thereof for effectively compression-encoding video data that has been processed with the inverse 2:3 pull-down process.
A telecine unit that converts a film material recorded on an optical film for a movie and so forth into a television signal has been proposed. Generally, on a film material that is used for a movie theater, pictures have been recorded at a frame rate of 24 Hz (24 frames per second). Thus, the frame rate of a film material is completely different from that of an NTSC format television signal at a frame rate of 29.97 Hz. Thus, in the telecine unit, a process for converting 24 frames into 30 frames is performed. In such a process, two fields of an original film material are converted into three fields in a predetermined sequence. Thus, such a process is referred to as 2:3 pull-down process. In reality, a particular field of an original film material is repeated in a predetermined sequence. The repeated field is inserted between fields of the original film material (hereinafter, the repeated field is referred to as repeat field). Thus, with the film material at a frame rate of 24 Hz, a television signal at a frame rate of 30 Hz is generated.
Video data converted into a television signal by the telecine unit is compression-encoded by a compression-encoding technique such as MPEG encoding method. The encoded video stream is recorded on a record medium or transmitted to a transmission medium. Before video data that has been processed with the 2:3 pull-down process is compression-encoded, the repeat fields are removed so as to improve the compression-encoding efficiency. This is because the repeat fields are redundant fields that have been added with the 2:3 pull-down process. Thus, even if these repeat fields are removed, the picture quality does not deteriorate. A process for removing redundant fields added with the 2:3 pull-down process is referred to as inverse 2:3 pull-down process.
To remove repeat fields in the inverse 2:3 pull-down process, the repeat fields should be detected. To detect repeat fields, a simple algorithm is used. In the algorithm, the luminance difference between two fields (first and second fields) is calculated. When the luminance difference is almost xe2x80x9c0xe2x80x9d, it is determined that the second field is a repeat field.
However, since video data that has been processed with the 2:3 pull-down process is data of which a material optically recorded on an optical film is converted into a television data, the video data contains noise due to a miss-alignment of the film or dust and stain thereof. Thus, when video data that has been processed with the 2:3 pull-down process is processed with the inverse 2:3 pull-down process by a conventional repeat field detecting algorithm, if noise contained in the video data is small, repeat fields can be accurately detected. However, if noise contained in the video data is very large, normal fields (=not repeat fields) may be incorrectly determined as repeat fields.
In a broadcasting station, a video program production company, and so forth, video data generated from film material is not transmitted without editing process as a television program. Instead, a television program is generated by inserting new video data such as commercial program in the video data generated from film material by video editing process. The new video data is not video data generated from a film material, but video data (with a frame frequency of 29.97 Hz) that has been shot by a video camera or the like. In other words, the edited video program is including both video data generated from a film material by the 2:3 pull-down process (the frame frequency of the original material is 24 Hz) and normal video data (the frame frequency of the original material is 29.97 Hz).
When the inverse 2:3 pull-down process is performed for the edited video program using the above-described repeat field detecting algorithm, as long as the above-described noise is not abnormally large, repeat fields are removed from the video data generated from the film material. However, when the inverse 2:3 pull-down process is performed using the repeat field detecting algorithm, normal fields may be detected as repeat fields. When new inserted video data is similar to a still picture rather than moving picture, the probability of which normal fields are incorrectly detected as repeat fields becomes high.
In other words, in the conventional inverse 2:3 pull-down process, normal fields may be incorrectly detected as repeat fields. Thus, in the conventional inverse 2:3 pull-down process, repeat fields cannot be accurately removed. When normal fields are determined as repeat fields, the normal fields are removed from video data that has been processed with the inverse 2:3 pull-down process. As a result, field drop-outing of the normal field may occur.
Unlike with a storage system that records a supplied source material to a storage medium, in a digital broadcasting system, a source material should be processed and transmitted to individual subscribers on real time basis. Moreover, in the digital broadcasting system, the field drop-outing should be avoided from taking place in video data. In other words, in the digital broadcasting system, video data free of unnatural motion should be transmitted as an essential condition. The requirement of video data free of unnatural motion is superior to the requirement of the transmission efficiency using the inverse 2:3 pull-down process.
Thus, in a conventional digital broadcasting system, to completely prevent the field drop-outing from taking place in transmission video data, the inverse 2:3 pull-down process has not been performed at all. Consequently, the compression efficiency deteriorates by around 25% in comparison with the case that repeat fields are fully removed.
Therefore, an object of the present invention is to provide a video data processing apparatus and a video data processing method for performing an inverse 2:3 pull-down process for video data that has been processed with a 2:3 pull-down process in the case that video data generated from a film material is compression-encoded and broadcast free from a frame skip due to an incorrect detection of a repeat field.
Another object of the present invention is to provide a video data encoding apparatus and a video data encoding method for performing the above-described inverse 2:3 pull-down process and for performing a compression-encoding process for video data with high compression efficiency.
To accomplish the above object, claim 1 of the present invention is a video data processing apparatus for removing a repeat field from video data, comprising a repeat field detecting means for detecting the repeat field contained in the video data, an analyzing means for analyzing a pattern of the repeat field contained in the video data corresponding to the detected results of the repeat field detecting means and determining whether the pattern of the repeat field is continuous or discontinuous, a video data processing means for removing the repeat field contained in the video data, and a controlling means for controlling the video data processing means to remove a field determined as a repeat field by the repeat field detecting means from the video data in a period that the patten of the repeat field is determined continuous by the analyzing means and for controlling the video data processing means not to remove a field determined as a repeat field by the repeat field detecting means from the video data in a period that the pattern of the repeat field is determined discontinuous by the analyzing means.
Another aspect of the present invention is a video data processing apparatus for removing a repeat field from video data, comprising a repeat field detecting means for detecting the repeat field contained in the video data, an analyzing means for determining whether or not an occurrence sequence of the repeat field contained in the video data is regular corresponding to the detected results of the repeat field detecting means, a video data processing means for removing the repeat field contained in the video data, and a controlling means for controlling the video data processing means to remove a field determined as a repeat field by the repeat field detecting means from the video data in a period that the occurrence sequence of the repeat field is determined regular by the analyzing means and for controlling the video data processing means not to remove a field determined as a repeat field by the repeat field detecting means from the video data in a period that the occurrence sequence of the repeat field is determined irregular by the analyzing means.
Another aspect of the present invention is a video data processing apparatus for processing video data of which a first video material of which an original material is processed with 2 3 pull-down process and a second video material of an original material with a frequency of a normal television signal coexist, comprising an analyzing means for analyzing a repetitive pattern of the repeat field contained in the video data and determining whether a current field of the video data is a field of the first video material or a field of the second video material, a video data processing means for removing the repeat field from the video data, and a controlling means for controlling the operation of the video data processing means corresponding to the analyzed results of the analyzing means.
Another aspect of the present invention is a video data processing apparatus for processing video data field by field, a progressive-scanned video material and an interlace-scanned video material coexisting in the video data, comprising an analyzing means for analyzing the continuity of a repeat field contained in the video data and determining whether the current field of the video data is a field of the progressive-scanned video material or a field of the interlace-scanned video material, a video data processing means for removing the repeat field from the video data, and a controlling means for controlling the video data processing means to remove a repeat field contained in the progressive-scanned video material and not to remove a field contained in the interlace-scanned video material corresponding to the analyzed results of the repeat field analyzing means.
Another aspect of the present invention is a video data processing method for removing a repeat field from video data, comprising the steps of detecting the repeat field contained in the video data, analyzing a pattern of the repeat field contained in the video data corresponding to the detected results of the repeat field detecting step and determining whether the pattern of the repeat field is continuous or discontinuous, removing the repeat field contained in the video data, and controlling the video data processing step to remove a field determined as a repeat field by the repeat field detecting step from the video data in a period that the patten of the repeat field is determined continuous by the analyzing step and the video data processing step not to remove a field determined as a repeat field by the repeat field detecting step from the video data in a period that the pattern of the repeat field is determined discontinuous by the analyzing step.
Another aspect of the present invention is a video data processing method for removing a repeat field from video data, comprising the steps of detecting the repeat field contained in the video data, determining whether or not an occurrence sequence of the repeat field contained in the video data is regular corresponding to the detected results of the repeat field detecting step, removing the repeat field contained in the video data, and controlling the video data processing step to remove a field determined as a repeat field by the repeat field detecting step from the video data in a period that the occurrence sequence of the repeat field is determined regular by the analyzing step and the video data processing step not to remove a field determined as a repeat field by the repeat field detecting step from the video data in a period that the occurrence sequence of the repeat field is determined irregular by the analyzing step.
Another aspect of the present invention is a video data processing method for processing video data of which a first video material of which an original material is processed with 2 3 pull-down process and a second video material of an original material with a frequency of a normal television signal coexist, comprising the steps of analyzing a repetitive pattern of the repeat field contained in the video data and determining whether a current field of the video data is a field of the first video material or a field of the second video material, removing the repeat field from the video data, and controlling the operation of the video data processing means corresponding to the analyzed results of the analyzing step.
Another aspect of the present invention is a video data processing method for processing video data field by field, a progressive-scanned video material and an interlace-scanned video material coexisting in the video data, comprising the steps of analyzing the continuity of a repeat field contained in the video data and determining whether the current field of the video data is a field of the progressive-scanned video material or a field of the interlace-scanned video material, removing the repeat field from the video data, and controlling the video data processing step to remove a repeat field contained in the progressive-scanned video material and not to remove a field contained in the interlace-scanned video material corresponding to the analyzed results of the repeat field analyzing step.
Another aspect of the present invention is a video data encoding apparatus for encoding video data in which a repeat field is placed in a predetermined sequence, comprising, an analyzing means for analyzing a pattern of the repeat field contained in the video data and determining whether or not the pattern of the repeat field is continuous, a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that is output from the video data processing means, and a controlling means for controlling the video data processing means to remove a field determined as a repeat field by the repeat field detecting means and perform an encoding process in a frame prediction mode and a frame DCT mode in a period that the pattern of the repeat field is determined continuous by the analyzing means and for controlling the video processing means not to remove a field determined as a repeat field by the repeat field detecting means and perform an encoding process in one of a frame prediction mode and a field prediction mode and one of a frame DCT mode and a field DCT mode in a period that the pattern of the repeat field is determined discontinuous by the analyzing means.
Another aspect of the present invention is a video data encoding apparatus for encoding video data of which a first video material of which an original material is processed with 2:3 pull-down process and a second video material of an original material with a frequency of a normal television signal coexist, comprising an analyzing means for analyzing a repetitive pattern of the repeat field contained in the video data and determining whether the current field of the video data is a field of the first video material or a field of the second video material, a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that is output from the video data processing means, and a controlling means for controlling an operation of the video data processing means and an encoding mode of the encoding means corresponding to the analyzed results of the analyzing means.
Another aspect of the present invention is a video data encoding apparatus for encoding video data of which a progressive-scanned video material and an interlace-scanned video material coexist, comprising an analyzing means for analyzing the continuity of a repeat field contained in the video data and determining whether the video data is the progressive-scanned video data or the interlace-scanned video data, a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that is output from the video data processing means, and a controlling means for controlling the video data processing means to remove a repeat field contained in the progressive-scanned video material and not to remove a field contained in the interlace-scanned video material corresponding to the analyzed results of the analyzing means and for controlling the encoding means to select an encoding mode corresponding to the progressive-scanned video material or the interlace-scanned video material.
Another aspect of the present invention is a video data encoding apparatus for encoding video data of which a progressive-scanned video material and an interlace-scanned video material coexist, comprising an analyzing means for analyzing the continuity of a repeat field contained in the video data and determining whether the video data is the progressive-scanned video data or the interlace-scanned video data, a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that is output from the video data processing means, and a controlling means for controlling the video data processing means to remove a repeat field contained in the video data and the encoding means to perform an encoding process in an encoding mode corresponding to the progressive-scanned video material when the video data is determined as the progressive-scanned video material by the analyzing means and for controlling the video data processing means not to remove a repeat field contained in the video data and the encoding means to perform an encoding process in an encoding mode corresponding to the interlace-scanned video material when the video data is determined as the interlace-scanned video material by the analyzing means.
Another aspect of the present invention is a video data encoding apparatus for encoding video data in which a repeat field is placed, comprising a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that has been processed by the video data processing means, and a controlling means for analyzing the continuity of a repeat field contained in the video data, determining whether a pattern of the repeat field contained in the video data is continuous or discontinuous, and controlling an operation of the video data processing means and an encoding mode of the encoding means.
Another aspect of the present invention is a video data encoding apparatus for encoding video data in which a repeat field is placed, comprising a video data processing means for removing the repeat field from the video data, an encoding means for encoding video data that has been processed by the video data processing means, and a controlling means for analyzing the continuity of a repeat field contained in the video data, determining whether an original material of the video data is a progress-scanned video material or interlace-scanned video data, and controlling an operation of the video data processing means and an encoding mode of the encoding means.
Another aspect the present invention is a video data encoding method for encoding video data in which a repeat field is placed in a predetermined sequence, comprising the steps of analyzing a pattern of the repeat field contained in the video data and determining whether or not the pattern of the repeat field is continuous, removing the repeat field from the video data, encoding video data that is output from the video data processing step, and controlling the video data processing step to remove a field determined as a repeat field by the repeat field detecting step and perform an encoding process in a frame prediction mode and a frame DCT mode in a period that the pattern of the repeat field is determined continuous by the analyzing step and for controlling the video processing step not to remove a field determined as a repeat field by the repeat field detecting step and perform an encoding process in one of a frame prediction mode and a field prediction mode and one of a frame DCT mode and a field DCT mode in a period that the pattern of the repeat field is determined discontinuous by the analyzing step.
Another aspect of the present invention is a video data encoding method for encoding video data of which a first video material of which an original material is processed with 2 3 pull-down process and a second video material of an original material with a frequency of a normal television signal coexist, comprising the steps of analyzing a repetitive pattern of the repeat field contained in the video data and determining whether the current field of the video data is a field of the first video material or a field of the second video material, removing the repeat field from the video data, encoding video data that is output from the video data processing step, and controlling an operation of the video data processing step and an encoding mode of the encoding step corresponding to the analyzed results of the analyzing step.
Another aspect of the present invention is a video data encoding method for encoding video data of which a progressive-scanned video material and an interlace-scanned video material coexist, comprising the steps of analyzing the continuity of a repeat field contained in the video data and determining whether the video data is the progressive-scanned video data or the interlace-scanned video data, removing the repeat field from the video data, encoding video data that is output from the video data processing step, and controlling the video data processing step to remove a repeat field contained in the progressive-scanned video material and not to remove a field contained in the interlace-scanned video material corresponding to the analyzed results of the analyzing step and for controlling the encoding step to select an encoding mode corresponding to the progressive-scanned video material or the interlace-scanned video material.
Another aspect of the present invention is a video data encoding method for encoding video data of which a progressive-scanned video material and an interlace-scanned video material coexist, comprising the steps of analyzing the continuity of a repeat field contained in the video data and determining whether the video data is the progressive-scanned video data or the interlace-scanned video data, removing the repeat field from the video data, encoding step for encoding video data that is output from the video data processing step, and controlling the video data processing step to remove a repeat field contained in the video data and the encoding step to perform an encoding process in an encoding mode corresponding to the progressive-scanned video material when the video data is determined as the progressive-scanned video material by the analyzing step and for controlling the video data processing step not to remove a repeat field contained in the video data and the encoding step to perform an encoding process in an encoding mode corresponding to the interlace-scanned video material when the video data is determined as the interlace-scanned video material by the analyzing step.
Another aspect of the present invention is a video data encoding method for encoding video data in which a repeat field is placed, comprising the steps of removing the repeat field from the video data, encoding video data that has been processed by the video data processing step, and analyzing the continuity of a repeat field contained in the video data, determining whether a pattern of the repeat field contained in the video data is continuous or discontinuous, and controlling an operation of the video data processing step and an encoding mode of the encoding step.
A final aspect of the present invention is a video data encoding method for encoding video data in which a repeat field is placed, comprising the steps of removing the repeat field from the video data, encoding video data that has been processed by the video data processing step, and analyzing the continuity of a repeat field contained in the video data, determining whether an original material of the video data is a progress-scanned video material or interlace-scanned video data, and controlling an operation of the video data processing step and an encoding mode of the encoding step.